264 research outputs found
Hyperbranched {DNA} clusters
No full textTaking advantage of the base-pairing specificity and tunability of DNA interactions, we investigate the spontaneous formation of hyperbranched clusters starting from purposely designed DNA tetravalent nanostar monomers, encoding in their four sticky ends the desired binding rules. Specifically, we combine molecular dynamics simulations and Dynamic Light Scattering experiments to follow the aggregation process of DNA nanostars at different concentrations and temperatures. At odds with the Flory– Stockmayer predictions, we find that, even when all possible bonds are formed, the system does not reach percolation due to the presence of intracluster bonds. We present an extension of the Flory– Stockmayer theory that properly describes the numerical and experimental results
Cold-swappable DNA gels
No full textWe report an experimental investigation of an all-DNA gel composed by
tetra-functional DNA nanoparticles acting as network nodes and
bi-functional ones acting as links. The DNA binding sequence is designed
to generate at room and lower temperatures a persistent long-lived
network. Exploiting ideas from DNA-nanotechnology, we implement in the
binding base sequences an appropriate exchange reaction which allows
links to swap, constantly retaining the total number of network links.
The DNA gel is thus able to rearrange its topology at low temperature
while preserving its fully-bonded configuration
DEBORA: Developing an Interface to Support Collaboration in a Digital Library
No full textInterfaces to library systems have largely failed to represent the in-herently collaborative nature of information work. This paper describes how collaborative functionality is being implemented as part of the DEBORA project to provide access to digitised Renaissance documents. Work practices of users of Renaissance documents are described and the collaborative features of the client software are outlined. Functionalities discussed include annotation, the creation of virtual books and the inclusion of user-supplied metadata
Surface-Enhanced Raman Scattering of DNA-Nanoparticle assemblies
No full textDuring the last years, soft matter colloids have gained important achievements and a large amount of results have been accomplished to the realisation of innovative and smart nanomaterials. In particular, the understanding in the mastering of DNA-nanoparticle systems, which combine the plasmonic properties of metallic nanoparticles (NPs) with the programmability and self-assembly of DNA strands – opens up a great number of applications in different branches of science, especially in nanoscience. Consequently, the importance of Surface Enhanced Raman Scattering (SERS), which associates a high sensitivity and a specific spectral signature of DNA, is significantly increasing in the detection of specific targets, thus, in the implementation of high-quality biosensors. The DNA base-pairing specificity (A-T, C-G) allows the breakthrough in “programmable bonds” between nanoparticles, serving as the basic building blocks for the creation of mesoscopic plasmonic aggregates.
In our labs we provided to the realisation of DNA-NP structures by properly functionalizing metallic gold NPs with complementary and purposely programmed single-stranded DNA. To this aim, we have chosen two specific single-stranded DNA sequences, consisting of 12 base oligomers, with a thiolgroup at the end of each one which allows to covalent bond onto the metallic NP surfaces; the
aforementioned sequence assures not only a harder and more reproducible bond but also a more controllable adherence. Therefore, it has been possible an ensuing study of the spectroscopic features of these binary systems through the use of SERS. We have thus characterised the SERS spectrum for both DNA sequences-which were attached on gold NPs and obtained a coherent and reproducible signal. The spectra were obtained by using a direct and label-free protocol, thus, avoiding the loss of information about the intrinsic chemical and structural properties of DNA oligonucleotides that fluorescence methods cause. In addition, we provided the realisation of DNA-nanoparticle aggregates, starting from gold nanoparticles functionalized with the two different 12-base DNA
sequences and let them hybridise through the addition of a DNA ‘bridge’ which is a 24 base oligomers complementary to the two chains
Treatment of kidney clear cell carcinoma, lung adenocarcinoma and glioblastoma cell lines with hydrogels made of DNA nanostars
No full textOvercoming the systemic administration of chemotherapy to reduce drug toxicity and the application of personalised medicine are two of the major challenges in the treatment of cancer. To this aim, efforts are focused on finding novel nanomaterials for the targeted administration of drugs and bioactive molecules in the tumor sites. DNA-based hydrogels are promising candidates for these applications. However, while such materials are fairly known from a structural and physical standpoint, their effects on cell cultures are far less investigated. Here, we studied the biological response of three different cell lines (clear cell renal cell carcinoma 786-O, lung adenocarcinoma H1975 and glioblastoma U87MG) to the treatment with DNA-GEL - a DNA-based hydrogel composed of interacting DNA nanostars. Additionally, we investigated the structural modification of DNA-GELs under cell culture conditions. The results we collected show a cell type specificity of the response, with interesting implications for future applications
Surface-Enhanced Raman Scattering of DNA-Nanoparticle assemblies
No full textDuring the last years, soft matter colloids have gained important achievements and a large amount of results have been accomplished to the realisation of innovative and smart nanomaterials. In particular, the understanding in the mastering of DNA-nanoparticle systems, which combine the plasmonic properties of metallic nanoparticles (NPs) with the programmability and self-assembly of DNA strands – opens up a great number of applications in different branches of science, especially in nanoscience. Consequently, the importance of Surface Enhanced Raman Scattering (SERS), which associates a high sensitivity and a specific spectral signature of DNA, is significantly increasing in the detection of specific targets, thus, in the implementation of high-quality biosensors. The DNA base-pairing specificity (A-T, C-G) allows the breakthrough in “programmable bonds” between nanoparticles, serving as the basic building blocks for the creation of mesoscopic plasmonic aggregates.
In our labs we provided to the realisation of DNA-NP structures by properly functionalizing metallic gold NPs with complementary and purposely programmed single-stranded DNA. To this aim, we have chosen two specific single-stranded DNA sequences, consisting of 12 base oligomers, with a thiolgroup at the end of each one which allows to covalent bond onto the metallic NP surfaces; the
aforementioned sequence assures not only a harder and more reproducible bond but also a more controllable adherence. Therefore, it has been possible an ensuing study of the spectroscopic features of these binary systems through the use of SERS. We have thus characterised the SERS spectrum for both DNA sequences-which were attached on gold NPs and obtained a coherent and reproducible signal. The spectra were obtained by using a direct and label-free protocol, thus, avoiding the loss of information about the intrinsic chemical and structural properties of DNA oligonucleotides that fluorescence methods cause. In addition, we provided the realisation of DNA-nanoparticle aggregates, starting from gold nanoparticles functionalized with the two different 12-base DNA
sequences and let them hybridise through the addition of a DNA ‘bridge’ which is a 24 base oligomers complementary to the two chains
Exploiting SERS sensitivity to monitor DNA aggregation properties
No full textIn the last decades. DNA has been considered far more than the system carrying the essential genetic instructions. Indeed, because of the remarkable properties of the base-pairing specificity and thermoreversibility of the interactions, DNA plays a central role in the design of innovative architectures at the nanoscale. Here, combining complementary DNA strands with a custom-made solution of silver nanoparticles, we realize plasmonic aggregates to exploit the sensitivity of Surface Enhanced Raman Spectroscopy (SERS) for the identification/detection of the distinctive features of DNA hybridization, both in solution and on dried samples. Moreover. SERS allows monitoring the DNA aggregation process by following the temperature variation of a specific spectroscopic marker associated with the Watson-Crick hydrogen bond formation. This temperature-dependent behavior enables us to precisely reconstruct the melting profile of the selected DNA sequences by spectroscopic measurements only. (C) 2020 Elsevier B.V. All rights reserved
On the avant-garde : Bruno Schulz and Debora Vogel
No full textIn his recent book devoted to the study of Schulz, Michał Paweł Markowski rebukes the scholars of Schulz that they have ignored the indebtedness of the write r in Hegel's philosophy, and at the same time he claims that it is hard to find in Schulz any evidence that he had actually read the philosopher. The author of the article argues the contrary: Hegelian themes are treated by Schulz with an ironic distance, and it is certain the w rite r read Hegel as his
closest friend, Debora Vogel, devoted her PhD dissertation to the author of The Phenomenology of Spirit. The influence of Hegel can be rather seen in Vogel's writings, as she
was fascinated by the avant-garde idea of progress pursued by the anonymous masses. Seemingly Schulz the bumpkin is behind but in the long run he went ahead of his friend,
because unlike her he stressed the subjective aspect of the avant-garde revolution. Jarzębski Wobec awangardy: Bruno Schulz i Debora Vogel
Homogenization of conservation laws with oscillatory source and non-oscillatory data
No full textWe consider a scalar conservation law with oscillatory, periodic source term and with oscillatory initial data.
For possibly resonant initial data, we prove a corrector-type result for this problem, extending a previous one by
the author [Asymptotic Anal. 46 (2006), 53-79]. Here we can relax the assumption of well-prepared data
interessi sociali, concorrenza e pluralismo istituzionale nei servizi pubblici locali
No full textThe article tries to truce the connection between Pubblic Administration and Local Pubblic Services in the perspective of an institutional and social pluralism. Moving from the analysis of the changes occured to State intervention in economy and the ineraction of pubblic and private sector, the Author analyse the most recent reforms of Local Pubblic Services'legislation and the impact of the new costitutional federalism in the role of the different level of governament in managing and regulating Pubblic Service
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